With the advancement of technology, portable electronic devices have become indispensable to our daily lives. Some portable electronic devices, such as mobile phones, substantially include at least one housing, which is detachable to enable battery or SIM card replacement. For example, U.S. Pat. No. 9,072,163 B2 discloses a housing assembly for a portable electronic device, wherein a housing can be easily mounted to and detached from a body of the portable electronic device.